Carry on action, maintain pace (4,4)
I believe the answer is:
keep step
'carry on action' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.
'maintain pace' is the wordplay.
'maintain' becomes 'keep' (synonyms).
'pace' becomes 'step' (synonyms).
'keep'+'step'='KEEP STEP'
Can you help me to learn more?
(Other definitions for keep step that I've seen before include "conform" , "maintain conformity" .)